class  Counter{
    public int count;
    public  void add(){
        synchronized(this) {
            count++;
        }
    }

     synchronized public static void func(){

    }
}


public class Demo3 {
    public static void main(String[] args) throws InterruptedException {
Counter counter=new Counter();
Thread t1=new Thread(()->{
    for (int i = 0; i < 50000; i++) {
        synchronized (counter){
            counter.add();
        }

    }
        });

        Thread t2=new Thread(()->{
            for (int i = 0; i < 50000; i++) {
                synchronized (counter){
                    counter.add();
                }

            }
        });
   t1.start();
   t2.start();
   t1.join();
   t2.join();
        System.out.println("counter="+counter.count);
        StringBuffer stringBuffer
    }
}
